Cannot logon to my website

Hello.

When I go to logon to my website I put in my username and password, it then takes me to a screen that says the below (which is new);

“Please solve this math problem to prove that you are not a bot. Once you solve it, you will need to log in again.

Prove your humanity: 2 + 10 = ”

When i answer it takes me back to the logon screen and then the cycle continues.
Can you please help???

Kind regards
Naomi